docs: def add_field(self, name, fragment_size=150, number_of_fragments=3, fragment_offset=None, order="score", type=None):
          """
          Add a field to Highlinghter
          """
          data = {}
          if fragment_size:
              data['fragment_size'] = fragment_size
          if number_of_fragments is not None:
              data['number_of_fragments'] = number_of_fragments
          if fragment_offset is not None:
              data['fragment_offset'] = fragment_offset
          if type is not None:
              data['type'] = type
          data['order'] = order
          self.fields[name] = data